Liquid crystal composition

ABSTRACT

The present application relates to a liquid crystal composition, a liquid crystal cell, a liquid crystal film, and methods of preparing the same. As an exemplary liquid crystal composition, according to the present application can provide a liquid crystal layer aligned without a special alignment layer. According to the liquid crystal composition, all of the liquid crystal cell, in which the liquid crystal layer is maintained in a non-polymerized state, and the liquid crystal film prepared by polymerizing the liquid crystal layer can be provided.

This application is a Continuation Bypass Application of InternationalPatent Application No. PCT/KR2013/000895, filed Feb. 4, 2013, whichclaims priority to and the benefit of Korean Patent Application Nos.10-2012-0010706 filed on Feb. 2, 2012 and 10-2013-0012595, filed Feb. 4,2013, in the Korean Intellectual Property Office, all of which arehereby incorporated by reference in their entirety.

TECHNICAL FIELD

The present application relates to a liquid crystal composition, aliquid crystal film and method of preparing the same.

BACKGROUND ART

A liquid crystal compound means an organic compound having opticalanisotropy and crystalline property in the molecular orientation. Theliquid crystal compound is filled in a panel of a display device, andthe like and rearranged by supply of voltage, whereby it may be used tocontrol quantity of light penetrating through the panel. Also, theliquid crystal compound is polymerized in an aligned state and therebymay be used for an optical film, and the like such as a retardationfilm. In such a case, an alignment layer may be used in order to impartan order to the liquid crystal compound and in order for the liquidcrystal compound to response regularly.

Generally, an alignment layer is formed by applying an aligning agentsuch as polyimide or polyvinyl alcohol on a substrate, and orientationis imparted by rubbing the alignment layer in a predetermined direction.Later, a polymerized liquid crystal compound is applied and alignedthereon to prepare a liquid crystal layer. However, since the rubbedalignment layer has insufficient adhesive strength to the liquid crystallayer, a problem in which the liquid crystal layer is peeled orcontracted in a severe environment, such as a high-temperature orhigh-humidity environment, may occur. Further, a rubbing method may haveproblems in which static electricity or scratch is easily generated dueto friction during a rubbing process, and fine dust can be generatedproblem from a rubbing fabric, and the like.

A non-contacting alignment method is known for solving the problems ofrubbing method, and Patent document 1 discloses a light alignment methodusing light irradiation. However, such a method is cumbersome because aprocess for forming a special alignment layer should be performed.

[Patent document 1] KR Patent No. 10-2012-0008425

DISCLOSURE Technical Problem

The present application is directed to provide a liquid crystalcomposition, a liquid crystal film and method of preparing the same.

Technical Solution

An embodiment of the present application provides a liquid crystalcomposition including a photo-alignment material including a halogenelement and a liquid crystal compound.

When the liquid crystal composition is used, a liquid crystal layerincluding a liquid crystal compound aligned without a special alignmentlayer may be formed. Further, the liquid crystal composition may form aliquid crystal layer and an alignment layer that is phase-separated fromthe liquid crystal layer in a one process at the same time. Accordingly,even though the alignment layer and the liquid crystal layer are formedfrom one type of composition, components of the alignment layer and theliquid crystal layer may be prevented from being mixed in one layer andaffecting mutual functions. In the present specification, the term

-

and

-separation

are substantially used as an identical meaning and may mean that a layerformed by substantially one component may be located or disposed on alayer formed by substantially other components. In addition, the term

layer formed by substantially one component

may mean that only one component presents in one layer or one componentis richer than other components.

A liquid crystal composition may include a photo-alignment materialincluding a halogen element. In the present specification, the term

-alignment

means a compound that is orientationally ordered in a predetermineddirection through light irradiation, and the like, and is capable ofaligning adjacent liquid crystals through an interaction, such as ananisotropic interaction in such an orientationally ordered state.

A photo-alignment material may be a unimolecular compound, monomercompound, an oligomer compound, or a polymer compound.

The photo-alignment material including the halogen element may be acompound including a photosensitive moiety and a halogen element.Examples of the photo-alignment material may include a compound that isorientationally ordered by a photo-crosslinking or photopolymerization,such as [2+2] cycloaddition, [4+4] cycloaddition, or photodimerization.In addition, examples of the compound that is orientationally ordered bythe photo-crosslinking or photopolymerization may include a cinnamatecompound, a coumarin compound, a cinnamamide compound, atetrahydrophthalimide compound, a maleimide compound, a benzophenonecompound, a diphenylacetylene compound, a compound having a chalconylmoiety as a photosensitive moiety (hereinafter, referred to as achalconyl compound), a compound having an anthracenyl moiety(hereinafter, referred to as an anthracenyl compound), and the like.

As an example, a photo-alignment material including a halogen elementmay be a compound including a unit represented by the following ChemicalFormula 1:

wherein n represents a number of 50 to 5,000 in the above ChemicalFormula 1 and R₁ and R₂ each independently represents hydrogen, halogen,an alkyl group, or a residue represented by the following ChemicalFormula 2, wherein at least one of the R₁ and R₂ represents a moietyrepresented by the following Chemical Formula 2,

wherein, R₃ represents an alkylene group or an alkylidene group in theabove Chemical Formula 2 and R₄ to R₈ each independently representshydrogen, halogen, an alkyl group, an alkoxy group, or an allyloxygroup, and at least one of the unit represented by the above ChemicalFormula 1 and moiety represented by the above Chemical Formula 2includes a halogen element as a substituent.

In the present specification, the term “halogen” may include fluorine,chlorine, bromine, iodine, and the like, unless particularly indicatedotherwise.

In addition, examples of the term “alkyl group” may include, unlessparticularly indicated otherwise, an alkyl group having 1 to 20 carbonatoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms,1 to 4 carbon atoms, 4 to 10 carbon atoms, or 6 to 9 carbon atoms. Suchan alkyl group may be a linear chain, branched-chain or ring-type.Examples of the “alkyl group” may include a methyl group, an ethylgroup, a propyl group, an isopropyl group, a butyl group, an isobutylgroup, a tert-butyl group, a pentyl group, a neopentyl group, acyclohexyl group, a hexyl group, an octyl group, a nonyl group, a decylgroup, and the like. The alkyl group may arbitrarily be substituted byat least one substituent.

Also, examples of the term “alkoxy group” may include, unlessparticularly indicated otherwise, an alkoxy group having 1 to 20 carbonatoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms,1 to 4 carbon atoms, 4 to 10 carbon atoms, or 6 to 9 carbon atoms. Suchan alkoxy group may be a linear chain, branched-chain or ring-type.Examples of the alkoxy group may include a methoxy group, an ethoxygroup, a propoxy group, an isopropoxy group, a butoxy group, anisobutoxy group, a tert-butoxy group, and the like. In addition, thealkoxy group may arbitrarily be substituted by at least one substituent.

In addition, examples of the term “alkylene group” or “alkylidene group”may include, unless particularly indicated otherwise, an alkylene groupor alkylidene group having 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1to 12 carbon atoms, 1 to 8 carbon atoms, 1 to 4 carbon atoms, 4 to 10carbon atoms, or 6 to 9 carbon atoms. Such an alkylene group oralkylidene group may be a linear chain, branched-chain or ring-type. Thealkylene group or alkylidene group may arbitrarily be substituted by atleast one substituent.

A mark

in the above Chemical Formula 2 may mean that the site thereof is linkedto a mother compound. For example, a mark

at the left of R₃ in the above Chemical Formula 2 may mean that the R₃is directly linked to norbornane of Chemical Formula 1.

A halogen element of the compound having a unit represented by the aboveChemical Formula 1 may be directly and covalently bonded to at least anyone site of R₁, R₂, and R₄ to R₈; or may be included in a state in whicha halogen element is substituted at a divalent moiety of R₃ orsubstituents of R₁, R₂, and R₄ to R₈.

As an example, at least one of R₄ to R₈ in Chemical Formula 2 may be ahalogen element, an alkyl group substituted by a halogen element or analkoxy group substituted by a halogen element.

The term “alkyl group substituted by a halogen element” may mean analkyl group, in which at least one of hydrogen of the aforementionedalkyl group is substituted by a halogen element, unless particularlyindicated otherwise. For example, the alkyl group, in which one ofhydrogen of a methyl group is substituted by a halogen element, may be afluoromethyl group, a chloromethyl group, a bromomethyl group, or aniodomethyl group. The alkyl group having a substituted halogen elementmay arbitrarily be substituted by at least one substituent besides ahalogen element.

Also, the term “alkoxy group substituted by a halogen element” may meanan alkoxy group, in which at least one of hydrogen of the aforementionedalkoxy group is substituted by a halogen element, unless particularlyindicated otherwise. For example, the alkoxy group, in which onehydrogen of a methoxy group is substituted by a halogen element, may bea fluoromethoxy group, a chloromethoxy group, a bromomethoxy group, oran iodomethoxy group. The alkoxy group substituted by a halogen elementmay arbitrarily be substituted by at least one substituent besides ahalogen element.

As an example, n in the above Chemical Formula 1 may represent a numberof 50 to 3,000 or 50 to 1,500. Also, R₁ and R₂ in Chemical Formula 1each independently represents hydrogen, halogen, an alkyl group, or amoiety represented by the above Chemical Formula 2, wherein at least oneof the R₁ and R₂ may be a moiety represented by the above ChemicalFormula 2. In addition, as another example, R₁ and R₂ each independentlyrepresents hydrogen, an alkyl group having 1 to 6 carbon atoms or amoiety represented by the above Chemical Formula 2, wherein at least oneof the R₁ and R₂ may be a moiety represented by the above ChemicalFormula 2.

As an example, R₃ in the above Chemical Formula 2 may be an alkylenegroup or alkylidene group having 1 to 4 carbon atoms. In addition, R₄ toR₈ each independently represents hydrogen, halogen, or an alkyl group,but at least one of the R₄ to R₈ may be halogen.

A compound having a unit represented by the above Chemical Formula 1 maybe homopolymer or copolymer. When the compound having the unitrepresented by the above Chemical Formula 1 is copolymer, a repeatingunit that is included in the photo-alignment material besides the unitrepresented by the above Chemical Formula 1 may include all of therepeating units formed from the monomers that are known in the prior artas long as the repeating units do not interrupt orientation of thephoto-alignment material.

In addition, an end of the compound having the unit represented byChemical Formula 1 may be formed as an end that is known in the priorart. As an example, the end of the above compound may be formed to havean alkyl group or alkoxy group.

When a photo-alignment material is a polymerized compound, the materialmay have a weight average molecular weight of about 10,000 g/mol to500,000 g/mol, for example, but the present invention is not limitedthereto. The term “weight average molecular weight” may mean aconversion value to a standard polystylene measured by a gel permeationchromatograph (GPC), and unless particularly indicated otherwise, amolecular weight may mean a weight average molecular weight.

A liquid crystal composition may include a liquid crystal compound. Inthe present specification, the term

liquid crystal

may mean a compound having a site capable of exhibiting liquidcrystalline properties, for example, a mesogen frame, and the like.

The liquid crystal composition may provide, for example, a liquidcrystal layer including an orientated liquid crystal compound in anon-polymerized state and an orientated liquid crystal compound in apolymerized state. Here, including the liquid crystal compound in anon-polymeric state may mean that the liquid crystal compound isincluded such that the liquid crystal compound may be rearranged by anexternal stimulus, for example, supply of voltage, and the like. Also,here, including the liquid crystal compound in a polymerized state maymean that the liquid crystal compound is included such that theorientation thereof is not modified by an external stimulus, and thelike. In other words, since the liquid crystal composition may providethe liquid crystal layers in a non-polymerized and a polymerized state,a type of the liquid crystal compound included in the liquid crystalcomposition may properly be selected in view of use of the liquidcrystal composition.

As an example, the liquid crystal composition used in the liquid crystallayer in a non-polymerized state may include a non-polymerized liquidcrystal compound or polymerized liquid crystal compound. In addition, asanother example, the liquid crystal composition used in the liquidcrystal layer in a polymerized state may include a polymerized liquidcrystal compound. In the present specification, the term

liquid crystal

may mean a liquid crystal compound without a polymerized functionalgroup, and the term “polymerized liquid crystal compound” may mean aliquid crystal compound including at least one polymeric functionalgroup.

As an example, examples of a polymerized functional group of apolymerized liquid crystal compound may include, for example, afunctional group including an ethylenically unsaturated double bond,which is capable of being polymerized or cross-linked by a free radicalreaction. Here, examples of the functional group of the polymerizedliquid crystal compound may include, for example, an alkenyl group, anepoxy group, a cyano group, a carboxyl group, an acryloyl group, amethacryloyl group, an acryloyloxy group, a methacryloyloxy group, andthe like. As an example, the polymerized liquid crystal compound mayinclude the type of one or the type of two or more functional groups ofa vinyl group, an allyl group, an acryloyl group, a methacryloyl group,an acryloyloxy group, and a methacryloyloxy group. Also, the polymerizedliquid crystal compound may include, for example, one, two, three, orfour or more above functional groups. As an example, the polymerizedliquid crystal compound may include one, two, or three above functionalgroups.

As an example, the non-polymerized liquid crystal compound orpolymerized liquid crystal compound may be a compound represented by thefollowing Chemical Formula 3:

wherein A represents a single bond, —COO—, or —OCO— in the aboveChemical Formula 3 and R₁₁ to R₂₀ each independently representshydrogen, halogen, an alkyl group, an alkoxy group, an alkoxycarbonylgroup, a cyano group, a nitro group, —U-Q-P or a substituent representedby the following Chemical Formula 4 and a pair of adjacent twosubstituents of R₁₁ to R₁₅ or a pair of adjacent two substituents of R₁₆to R₂₀ may be linked to each other to form benzene substituted to—U-Q-P. Also, here, U represents —O—, —COO—, —OCO— or —OCOO—, and Qrepresents an alkylene group or an alkylidene group and P represents analkenyl group, an epoxy group, a cyano group, a carboxyl group, anacryloyl group, a methacryloyl group, an acryloyloxy group ormethacryloyloxy group.

wherein B represents a single bond, —COO—, or —OCO— in the aboveChemical Formula 4 and R₂₁ to R₂₅ each independently representshydrogen, halogen, an alkyl group, an alkoxy group, a cyano group, anitro group or —U-Q-P, and here, U represents —O—, —COO—, —OCO— or—OCOO—, and Q represents an alkylene group or an alkylidene group and Prepresents an alkenyl group, an epoxy group, a cyano group, a carboxylgroup, an acryloyl group, a methacryloyl group, an acryloyloxy group, ormethacryloyloxy group as a polymerized functional group.

A mark

at the left of B in the above Chemical Formula 4 may mean that the B isdirectly linked to benzene represented by Chemical Formula 3.

The term

may mean that no special atom or atom group exists at a correspondingsite. For example, the term

in the above Chemical Formulas 3 and 4 means a case in which no specialatom exists at a site marked in A or B. For example, when A in ChemicalFormula 3 is a single bond, benzenes at both sides of A may directly belinked to form a biphenyl structure.

Examples of the term “alkenyl group” may include, unless particularlyindicated otherwise, an alkenyl group having 2 to 20 carbon atoms, 2 to16 carbon atoms, 2 to 12 carbon atoms, 2 to 8 carbon atoms, 2 to 4carbon atoms, 4 to 10 carbon atoms, or 6 to 9 carbon atoms. Such analkenyl group may be a linear chain, branched-chain or ring-type. Thealkenyl group may include, for example, a vinyl group, an allyl group, aprophenyl group, an isoprophenyl group, a butenyl group, a hexenylgroup, a cyclohexenyl group or an octenyl group, and the like. Also, thealkenyl group may arbitrarily be substituted by at least one ofsubstituent.

In the present specification, examples of the substituent capable ofbeing substituted by arbitrarily compound or substituent may includehalogen, a hydroxyl group, an alkyl group, an alkoxy group, an alkenylgroup, an epoxy group, a cyano group, a carboxyl group, an isocyanategroup, a mercapto group, an acryloyl group, a methacryloyl group, anacryloyloxy group, a methacryloyloxy group or an aryl group, and thelike, but the present invention is not limited thereto.

The term “aryl group” may mean, unless particularly indicated otherwise,a compound having a benzene ring or a structure formed by a condensationof at least two benzene rings, or monovalent moiety derived from aderivative thereof. Also, the term “aryl group” may be a conceptincluding a so-called aralkyl group, and the like. The aryl group mayinclude, for example, an aryl group having 6 to 22 carbon atoms or 6 to16 carbon atoms. Examples of the aryl group may include a phenyl group,a phenylethyl group, a phenylpropyl group, a benzyl group, a tolylgroup, a xylyl group or a naphthyl group, and the like. The aryl groupmay arbitrarily be substituted by at least one of substituent.

As an example, in the above Chemical Formulas 3 and 4, P may eachindependently represent an acryloyl group, a methacryloyl group, anacryloyloxy group or a methacryloyloxy group. Also, as another example,in the above Chemical Formulas 3 and 4, P may each independentlyrepresent an acryloyloxy group or a methacryloyloxy group.

As an example, when a liquid crystal compound is a non-polymerizedliquid crystal compound, the non-polymerized liquid crystal compound maybe a compound, in which R₁₁ to R₂₀ each independently representshydrogen, halogen, an alkyl group, an alkoxy group, an alkoxycarbonylgroup, a cyano group, a nitro group in Chemical Formula 3 or asubstituent represented by the following Chemical Formula 4. And, thenon-polymerized liquid crystal compound may be a compound, in which R₂₁to R₂₅ each independently represents hydrogen, halogen, an alkyl group,an alkoxy group, a cyano group or a nitro group in Chemical Formula 4.

As another example, when a liquid crystal compound is a polymerizedliquid crystal compound, at least one of R₁₁ to R₂₀ may be —U-Q-P in theabove Chemical Formula 3 or a substituent represented by the followingChemical Formula 4, and at least one pair of two adjacent substituentsin the R₁₁ to R₁₅ or two adjacent substituents in the R₁₆ to R₂₀ may belinked to each other to form a benzene substituted by —U-Q-P. In such acase, —U-Q-P or a moiety represented by Chemical Formula 4, in which atleast one of —U-Q-P or the moiety represented by Chemical Formula 4 maybe present in the above Chemical Formulas 3 and 4, may be present, forexample, at a site of R₁₃, R₁₈ or R₂₃, and for example, one or two—U-Q-P's or the moiety represented by Chemical Formula 4 may be present.In addition, besides —U-Q-P or the moiety represented by ChemicalFormula 4 in the compound represented by the above Chemical Formula 3 orthe moiety represented by Chemical Formula 4, a substituent may be, forexample, hydrogen, halogen, a linear or branched alkyl group having 1 to4 carbon atoms, a cycloalkyl group having 4 to 12 carbon atoms, a cyanogroup, an alkoxy group having 1 to 4 carbon atoms, or a nitro group. Asanother example, besides the —U-Q-P or the moiety represented byChemical Formula 4, a substituent may be chlorine, a linear or branchedalkyl group having 1 to 4 carbon atoms, a cycloalkyl group having 4 to12 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a cyanogroup.

A liquid crystal compound may be included in a proper content incomparison with a photo-alignment material including a halogen elementso that a proper layer-separation may be induced and stable orientationis possible. The liquid crystal compound may be included, for example,in an amount of 30 to 300 parts by weight, 40 to 300 parts by weight, 50to 300 parts by weight, 80 to 300 parts by weight, 90 to 300 parts byweight, 100 to 300 parts by weight, 150 to 300 parts by weight, 200 to300 parts by weight, 30 to 250 parts by weight, 40 to 250 parts byweight, 80 to 250 parts by weight, 90 to 250 parts by weight, 100 to 250parts by weight, or 200 to 250 parts by weight, relative to 100 parts byweight of a photo-alignment material including a halogen element.

In the above range, the liquid crystal compound may be stably alignedwithout a special alignment layer and may form a liquid crystal layerand an alignment layer that is layer-separated from the liquid crystallayer at the same time. Accordingly, the liquid crystal layer may beformed from the liquid crystal compound in a simplified process.

A liquid crystal composition may further include a proper initiator inview of usage purpose. As an example, when a liquid crystal layerincluding such a composition in a polymerized state as a liquid crystalcomposition is provided, a radical initiator or cation initiator capableof initiating a polymerization of the liquid crystal compound in theliquid crystal composition may be included in the liquid crystalcomposition. Also, as another example, even when the liquid crystallayer including the liquid crystal composition in a non-polymerizedstate is provided, a radical initiator or cation initiator capable ofinitiating an orientation reaction of a photo-alignment material in theliquid crystal composition may be included in the liquid crystalcomposition. However, in a case in which there is a potential for aliquid crystal compound to be polymerized by using a polymeric liquidcrystal compound as a liquid crystal compound, and the like, aninitiator may not be used.

The radical initiator may use a free radical initiator that is wellknown in the prior art. The free radical photoinitiator include, forexample, amino ketones, such as2-methyl-1-[4-(methylthio)phenyl]-2-(4-morpholinyl)-1-propanone and2-benzyl-2-(dimethylamino)-1-[4-(4-morpholinyl)phenyl]-1-butanone;benzoin ethers, such as benzoin methyl ether and benzoin isopropylether; substituted benzoin ethers, such as anisoin methyl ether;substituted acetophenones, such as 2,2-diethoxyacetophenone and2,2-dimethoxy-2-phenylacetophenone; substituted alpha-ketols, such as2-methyl-2-hydroxypropyophenone; aromatic phosphine oxides, such asbis(2,4,6-trimethylbenzoyl)phenyl phosphine oxide; aromatic sulfonylchlorides, such as 2-naphthalene-sulfonyl chloride; photoactive oximes,such as 1-phenyl-1,2-propanedione-2(O-ethoxycarbonyl)oxime; and thelike; and a mixture thereof, but the present invention is not limitedthereto.

A useful thermal free radical initiator includes, for example, azocompounds, such as 2,2′-azo-bis(isobutyronitrile), dimethyl2,2′-azo-bis(isobytyrate), azo-bis(diphenyl methane), and4,4′-azo-bis(4-cyanopentanoic acid); peroxides, such as peroxide,benzoyl peroxide, cumyl peroxide, tert-butyl peroxide, cyclohexanoneperoxide, glutartic acid peroxide, lauroyl peroxide, and methyl ethylketone peroxide; hydroperoxides, such as tert-butyl hydroperoxdie andcumene hydroperoxide; peroxy acids, such as peracetic acid, perbenzoicacid, persulphuric acid kalium, and persulphuric acid ammonium;peresters, such as diisopropyl and percarbonate; thermal redoxinititator; and the like; and a mixture thereof, but the presentinvention is not limited thereto.

As an example, a free radical initiator may include a free radicalphotoinitiator in view of availability of general use and simultaneousinitiation, solventless treatment possibility, storage stability, andthe like. For this reason, the free radical photoinitiator may include,for example, a free radical photoinitiator selected from amino ketone,substituted acetophenone, aromatic phosphine oxide, and a mixturethereof.

The cation initiator may use an initiator that is known in the priorart. A useful cation photoinitiator includes any various known usefulmaterials, for example, onium salt, a special organic metal complex, andthe like, and a mixture thereof. A useful onium salt includes one havinga structure formula, AX, and here, A is an organic cation (for example,may be selected from diazonium, iodonium, and sulfonium cation andspecifically, may be selected from diphenyliodonium, triphenylsulfonium,and phenylthiophenyl diphenylsulfonium), and X is an anion (for example,organic sulfonate, halogenated metal, or metalloid). Especially, auseful onium salt includes aryl diazonium salt, diaryliodonium salt, andtriaryl sulfonium salt, but the present invention is not limitedthereto. A useful cation thermal initiator includes quaternary ammoniumsalts of imidazole and superacid (for example, quaternary ammonium saltof SbF₆), and the like, and a mixture thereof. As an example, a cationinitiator may include a cation photoinitiator in view of availability ofgeneral use and simultaneous initiation, solventless treatmentpossibility, and storage stability. Among these, for this reason, it ispossible to use a cation photoinitiator selected from anium salts and amixture thereof.

A specific ratio of a radical initiator or cation initiator may properlybe selected, but the present invention is not specifically limited,according to purposes. For example, such an initiator may be included ina ratio of 0.01 parts by weight to 20 parts by weight, relative to 100parts by weight of a liquid crystal compound, but the present inventionis not limited thereto. When the ratio of initiator is extremely low, aproper polymerization may not be induced; on the contrary, when it isextremely high, physical properties may be deteriorated due to aresidual initiator after forming an alignment layer. Therefore, a properratio may be selected considering the above things.

Such a liquid crystal composition may be uniformly mixed and prepared ina proper solvent if necessary for a coating ability of the composition.As an example, when a specific solvent is used as a solvent capable ofbeing added in a liquid crystal composition, the specific solvent maycontrol such that a phase-separation easily occurs during application ofthe liquid crystal composition. Examples of the solvent may include oneor two or more of an ether solvent, an aromatic solvent, a halogensolvent, an olefin solvent, a ketone solvent, and the like. Examples ofthe solvent may include cyclopentanone, cyclohexanone, chlorobenzene,N-methylpyrrolidone, toluene, xylene, mesitylene, cymene,dimethylsulfoxide, dimethylformamide, chloroform, gamma butyrolactone,tetrahydrofuran, and the like.

The liquid crystal composition may further include properly any additivethat is known in the prior art, if necessary, in addition to theaforementioned components. Example of any additive may include a chiralagent, surfactant, polymerized monomer, polymer, and the like.

Another embodiment of the present application provides a liquid crystalfilm. Such a liquid crystal film may include a substrate layer; and aliquid crystal layer formed on the substrate layer, in which a liquidcrystal compound is present in an aligned state in the liquid crystallayer.

The substrate layer may be used without limitation as long as it is usedin the art. Especially, the substrate layer may be a substrate layerwithout orientation. However, the present invention is not limitedthereto, but it is possible to use a substrate having orientation as asubstrate layer. The term “orientation” may mean property capable oforienting adjacent liquid crystal molecules, liquid crystal compounds,or precursors thereof in a predetermined direction.

As the substrate layer, various types of substrates may be used. As anexample, the substrate layer may include an optically isotropysubstrate, an optically anisotropic substrate, such as a retardationlayer exhibiting retardation property, a polarizer element, and thelike.

An optically isotropy substrate may include a transparent substrate,such as a glass or transparent plastic substrate. Examples of theplastic substrate may include: cellulose substrates, such as diacetylcellulose (DAC) or triacetyl cellulose (TAC) substrate; cyclo olefincopolymer (COP) substrates, such as a norbornene derivative resinsubstrate; acrylic substrates, such as a poly(methyl methacrylate)(PMMA) substrate; polycarbonate (PC) substrates; olefin substrates, suchas a polyethylene (PE) or polypropylene (PP) substrate; polyvinylalcohol (PVA) substrates; poly ether sulfone (PES) substrates;polyetheretherketone (PEEK) substrates; polyetherimide (PEI) substrates;polyethylenenaphthalate (PEN) substrates; polyester substrates, such asa polyethyleneterephthalate (PET) substrate; polyimide (PI) substrates;polysulfone (PSF) substrates; polyarylate (PAR) substrates; fluorineresin substrates; and the like. The substrates may have, for example, asheet or film shape.

An optically anisotropic substrate, for example, a retardation layer,may include, for example, a ¼ wavelength layer, a ½ wavelength layer,and the like. The term “n wavelength layer” may mean a retardationelement capable of performing a retardation of light incident to thewavelength layer to such an extent as to be n-times of wavelengththereof. The retardation layer may be a liquid crystal polymer layerformed by orienting and polymerizing a polymerized liquid crystalcompound, or a plastic film or sheet having birefringence given by anelongation process, a contraction process, and the like.

A polarized element may use a general element that is known in the priorart. For example, the polarized element may use an element prepared byabsorbing and orienting a dichroic dye, and the like to a polyvinylalcohol resin.

For the substrate, various surface treatments, such as a low reflectiontreatment, an anti-reflection treatment, an anti-glare treatment, and/ora high resolution anti-glare treatment may be performed, if necessary.

As an example, a liquid crystal layer may be formed by theaforementioned liquid crystal composition. The liquid crystal layer mayinclude an aligned liquid crystal compound. The liquid crystal compoundmay be aligned, for example, in a homogeneous, homeotropic, tilted,splay, or cholesteric type.

The liquid crystal layer formed of the liquid crystal composition may beincluded in a state of being phase-separated from the liquid crystalcompound in a state of orientationally ordering a photo-alignmentmaterial in the liquid crystal layer. In other words, the liquid crystallayer may include a layer that is phase-separated from the liquidcrystal compound in a state of orientationally ordering aphoto-alignment material, and a layer composed of the liquid crystalcompound aligned by a layer formed by the photo-alignment material. Thepresent specification, the layer formed by the photo-alignment materialis called an alignment layer. And, the liquid crystal layer may meanonly a layer formed by a phase-separated liquid crystal compound in anarrow sense, but the liquid crystal layer may mean a layer including analignment layer and layer formed by the liquid crystal compound in abroad sense.

As described above, the liquid crystal composition may form a liquidcrystal layer and an alignment layer, thereby, the liquid crystalcomposition may form a liquid crystal layer including an aligned liquidcrystal compound even though a liquid crystal layer is formed withoutforming a special alignment layer on a substrate layer withoutorientation. In other words, for the liquid crystal film, the substratelayer may be a substrate layer without orientation, and the liquidcrystal layer may be a liquid crystal layer that is formed adjacent tothe substrate layer.

For the liquid crystal layer, the liquid crystal compound may beincluded in the liquid crystal layer in a non-polymerized state orpolymerized state.

As an example, when a liquid crystal compound is included in a liquidcrystal layer in a non-polymerized state, an aligned state of the liquidcrystal compound may be switched by supply of voltage. The presentspecification, the term “liquid crystal film” may be used as a meaningincluding a liquid crystal layer composed of non-polymerized liquidcrystal compound and polymerized liquid crystal compound, butespecially, a liquid crystal film including a liquid crystal layercomposed of a non-polymerized liquid crystal compound may separately becalled a liquid crystal cell.

As another example, a liquid crystal layer may include an aligned liquidcrystal molecule. In the present specification, the term

liquid crystal molecule

may mean a liquid crystal polymer formed by polymerizing a polymerizedliquid crystal compound in an aligned state. The aligned state of theliquid crystal layer including the liquid crystal molecule may not bechanged by supply of voltage.

Another embodiment of the present application provides a method ofpreparing a liquid crystal film. The method of preparing the liquidcrystal film may include forming a liquid crystal layer by irradiatingpolarized light onto a coating layer including a liquid crystalcomposition, which is formed on a substrate layer. As an example, themethod of preparing the liquid crystal film may be a method of preparingthe liquid crystal film as aforementioned above.

The preparing method may further include forming a coating layer byapplying a liquid crystal composition on a substrate layer. Here, theliquid crystal composition may use the aforementioned liquid crystalcomposition. As an example, when a liquid crystal layer of anon-polymerized liquid crystal composition is formed, a liquid crystalcomposition including no initiator or a very small quantity of aninitiator may be used. As another example, when a liquid crystal layerof a polymerized liquid crystal compound is formed, a liquid crystalcomposition including an initiator may be used. The initiator may beused as described above.

A method of applying the liquid crystal composition on a substrate layermay use a general method, for example, a bar coating, a comma coating ora spin coating, and the like. The composition may be applied, forexample, in a thickness of about 0.01 μm to about 10 μm or about 0.1 μmto about 5 μm.

Subsequently, a coating layer including a liquid crystal composition maybe dried in proper condition. As an example, the drying condition may beperformed by maintaining the coating layer at a temperature of about 25°C. to 150° C. for about 30 seconds or more. When a drying temperature is25° C. or higher, the remaining solvent, and the like in the coatinglayer are sufficiently dried, and thereby spots, and the like, may beprevented. Also, when a drying temperature is 150° C. or less,modification of the substrate layer may be prevented.

After drying the coating layer, irradiation of light, for example,linearly polarized ultraviolet may be irradiated. Accordingly, aphoto-alignment material present on the coating layer may bephase-separated from the liquid crystal compound to form an alignmentlayer.

The irradiation of linearly polarized ultraviolet may be performed, forexample, by using a wire grid polarizer, and the like. In such aprocess, it is possible to control an alignment direction of analignment layer by controlling a polarization direction of ultraviolet.Also, such light may be irradiated for at least 0.5 seconds, forexample.

By such irradiation of light, a photo-alignment material including ahalogen element included in a dried composition may be orientated by,for example, a photo-crosslinking or photo-polymerization reaction.Also, the photo-alignment material including a halogen element may bemoved, for example, toward a light irradiation direction in the coatinglayer, thereby being layer-separated from a liquid crystal compound.Therefore, the light irradiation direction may be controlled in view ofthe position to form an alignment layer from a photo-alignment material.As an example, as illustrated in FIG. 1, when light is irradiated ontothe side opposite to the side having a substrate layer (101) among oneside of a coating layer (12), a liquid crystal film having a liquidcrystal layer (102) between an alignment layer (103) and the substratelayer (101) may be formed.

Also, in a light irradiation process, a liquid crystal compound may belayer-separated from a liquid crystal compound, and may be aligned by analignment layer aligned according to a polarization direction ofpolarized ultraviolet.

As an example, in order to increase orientation of a liquid crystallayer after an alignment treatment, at least one drying process may beperformed again. A coating membrane of a liquid crystal composition maybe alignment-treated to form an alignment layer and liquid crystallayer, which are layer-separated, and subsequently, the layer-separatedalignment layer and liquid crystal layer may be dried to induce anon-aligned liquid crystal compound, which is likely to be remained inthe liquid crystal layer, to be aligned.

In such a process, when a liquid crystal composition including theaforementioned initiator is used as a liquid crystal composition, aliquid crystal compound of the liquid crystal layer may be polymerizedin a step of irradiating polarized ultraviolet. However, the presentinvention is not limited thereto, and a special polymerization processmay further be performed, if necessary, in order to polymerize theliquid crystal compound of the liquid crystal layer. As an example,after a step of irradiating polarized light onto the coating layer,subsequently, a liquid crystal compound of the liquid crystal layer maybe polymerized by irradiating light, for example, non-polarizedultraviolet on the liquid crystal layer. Such a polymerization may beperformed under the presence of a cation initiator or radical initiatorabsorbing a wavelength of ultraviolet region.

Ultraviolet irradiation may be performed in the atmosphere, or under thenitrogen atmosphere blocking oxygen in order to increase reactionefficiency. In general, the ultraviolet irradiation may be performed byusing a medium pressure or high pressure mercury UV lamp or a metalhalide lamp having strength of 80 mW/cm² or higher as an ultravioletirradiator. If necessary, a cold mirror or other cooling devices may beinstalled between an ultraviolet lamp and a substrate layer so that atemperature of a liquid crystal layer is in the range, in which theliquid crystal layer is in a liquid crystal state during the ultravioletirradiation.

The method of preparing the liquid crystal film may further include aprocess that is generally performed in the prior art, except that analignment layer and a liquid crystal layer are formed of one type of aliquid crystal composition by using one process.

It is possible to apply the liquid crystal film to various technicalfields. For example, it is possible to apply the liquid crystal film toa display device, and the like. The liquid crystal film may be useful,for example, as an optical compensation substrate for a display deviceor a liquid crystal panel, such as a display device. Accordingly, theliquid crystal film may be included in such a device as a liquid crystalpanel or an optical compensation substrate.

When the liquid crystal film is included in such a device as an opticalcompensation substrate, the film may include, for example, a retardationfilm, such as a super twist nematic (STN) LCD, a thin filmtransistor-twisted nematic (TFT-TN) LCD, a vertical alignment (VA) LCD,or an In-plane switching (IPS) LCD, and the like; a λ/2 wavelengthplate; λ/4 wavelength plate; a reverse wave dispersion property film; anoptical compensation film; a color film; a laminated film with apolarizing plate or a polarizer; a polarizing plate compensation film,and the like.

A method of constituting a display device by using such a film accordingto use of the liquid crystal film is not specifically limited. There arevarious known methods of constituting a place or a device, in which thefilm is located inside the device according to use of the liquid crystalfilm in the field, and all of the methods may be applied.

As a display device including the liquid crystal film, a liquid crystaldisplay device will be illustrated as follows.

A liquid crystal display device includes a liquid crystal panel, and afirst and second polarizing plate that are disposed on both sides of theliquid crystal panel, respectively. The liquid crystal film may bedisposed between the liquid crystal panel and the first polarizing plateand/or the liquid crystal panel and the second polarizing plate.

Here, a protecting film may be included on one side or both sides of thefirst and/or second polarizing plate. The protecting film may include aTAC film, a polynorbornene film prepared by a ring opening metathesispolymerization (ROMP), a ring opening metathesis polymerization followedby hydrogenation (HROMP) polymer prepared by again hydrogenating ringopening polymerized cycloolefin polymer (COP), a polyester film, or apolynorbornene-based film prepared by an addition polymerization, andthe like. Besides, a film prepared by a transparent polymer material maybe used as a protecting film, but the present invention is not limitedthereto.

Advantageous Effects

As an exemplary liquid crystal composition of the present applicationcan provide a liquid crystal layer aligned without a separate alignmentlayer. According to the liquid crystal composition, all of the liquidcrystal cell, in which the liquid crystal layer is maintained in anon-polymerized state, and the liquid crystal film prepared bypolymerizing the liquid crystal layer can be provided.

DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram illustrating parts of a method ofpreparing an exemplary liquid crystal film.

FIGS. 2 to 4 are polarizing microscope images illustrating the liquidcrystal films prepared in Examples 1, 2, and Comparative Example 1,respectively.

FIG. 5 is a diagram illustrating a retardance (vertical axis) accordingto an incident angle (horizontal axis) of the liquid crystal filmprepared in Example 2.

FIGS. 6 to 8 are SEM images illustrating the cross sections of theliquid crystal films prepared in Examples 1, 2, and Comparative Example2, respectively.

BEST MODES OF THE INVENTION

Hereinafter, the liquid crystal composition will be described in furtherdetail with reference to the following Examples and ComparativeExamples, but the range of the composition is not limited to thefollowing Examples.

Hereinafter, physical properties for Examples and Comparative Exampleswere evaluated by using the following methods.

1. Evaluation of Liquid Crystal Orientation

In a state where penetration axes of two polarizing plates of apolarizing microscope are perpendicular to each other, a liquid crystalcell or a liquid crystal film prepared in Examples or ComparativeExamples was disposed between two polarizing plates. At this time, theliquid crystal cell or the liquid crystal film was disposed such that anoptical axis corresponded with the penetration axis of any onepolarizing plate among the above polarizing plates. In such adisposition state, when retardation did not occur on the liquid crystalcell or liquid crystal film, thereby uniformly orienting the liquidcrystal of the liquid crystal cell or liquid crystal film, there was noshine phenomenon between the polarizing plates, which were observed tobe black. Therefore, a degree of shine was evaluated by using CA210, adevice measuring luminance between the perpendicular polarizing platesin such a state, and liquid crystal orientation of the liquid crystalcell or liquid crystal film was evaluated on the basis of the degree ofshine. The images of polarizing microscopes of the liquid crystal cellsand liquid crystal film in Examples and Comparative Examples areillustrated in FIGS. 2 to 4.

<Evaluation Criteria>

O: a case of not observing shine

X: a case of observing shine

2. Evaluation of Liquid Crystal Fluidity

After applying pressure in the pressure degree of fingers on the liquidcrystal cells or liquid crystal films prepared in Examples orComparative Examples, it was confirmed whether the liquid crystal cellsor liquid crystal films were again maintained in an initial alignedstate. When the aligned states of the liquid crystal cells or liquidcrystal films were returned to an initial aligned state within about 5seconds, it was designated that there was liquid crystal fluidity.

<Evaluation Criteria>

O: a case of returning liquid crystal orientation of the liquid crystalcell or liquid crystal film to an initial aligned state within about 5seconds after applying pressure.

X: a case of not returning liquid crystal orientation of the liquidcrystal cell or liquid crystal film to an initial aligned state withinabout 5 seconds after applying pressure.

3. Layer-separation Evaluation

By confirming scanning electron microscope (SEM) images of cross sectionof a liquid crystal cell or liquid crystal film prepared in Examples orComparative Examples, it was evaluated whether layer-separation in theliquid crystal cell or liquid crystal film occurred. The SEM images ofExamples 1, 2, and Comparative Example 1 are illustrated in FIGS. 6 to8, respectively.

Example 1 (1) Preparation of Liquid Crystal Composition

A photo-alignment material including a repeating unit represented by thefollowing Chemical Formula B was mixed to a liquid crystal compoundrepresented by the following Chemical Formula A (Trade name: LC242,Manufacturer: BASF) in a ratio of 30 parts by weight, relative to 70parts by weight of the liquid crystal compound. Then, the mixture wasagain dissolved in toluene to be a solid concentration of 30% by weightto prepare a liquid crystal composition.

(2) Preparation of Liquid Crystal Cell

The liquid crystal composition was coated on one side of a TAC substratelayer (Refractive Index: 1.49, Thickness: 80,000 nm) to be a thicknessof about 2 μm after drying, and then heated in an oven at 60° C. for 2minutes to remove the solvent inside the coating membrane. Subsequently,a wire grid polarizing plate (manufactured by Moxtek) capable ofgenerating linearly polarized light in a predetermined direction waslocated on top of the dried coating membrane. Then, while the TACsubstrate layer was moved in a rate of about 3 m/min, ultraviolet (LightSource: using a high pressure mercury lamp having strength of 200mW/cm²) was irradiated onto the dried coating membrane to perform analignment treatment. Subsequently, in order to increase orientation ofthe liquid crystal layer, the liquid crystal layer was dried in an ovenat 100° C. for about 2 minutes to prepare a liquid crystal cell.

Example 2 (1) Preparation of Liquid Crystal Composition

A photo-alignment material including the repeating unit represented bythe above Chemical Formula B was mixed to the liquid crystal compoundrepresented by the above Chemical Formula A (Trade name: LC242,Manufacturer: BASF) in a ratio of 30 parts by weight, relative to 70parts by weight of the liquid crystal compound. Then, the mixture wasagain dissolved in cyclopentanone to be a solid concentration of 30% byweight. Then, a radical photoinitiator (Trade Name: IRGACURE 907,Manufacturer: Ciba-Geigy) was added in a rate of 0.5 parts by weight,relative to 100 parts by weight of the solid content to prepare a liquidcrystal composition.

(2) Preparation of Liquid Crystal Film

The liquid crystal composition prepared in Example 2 was coated on oneside of a COP substrate layer (Refractive Index: 1.53, Thickness:100,000 nm) to be a thickness of about 2 μm after drying, and thenheated in an oven at 60° C. for 2 minutes to remove the solvent insidethe coating membrane. Subsequently, a wire grid polarizing plate(manufactured by Moxtek) capable of generating linearly polarized lightin a predetermined direction was located on the top of the dried coatingmembrane. Then, while the TAC substrate layer was moved in a rate ofabout 3 m/min, ultraviolet (Light Source: using a high pressure mercurylamp having strength of 200 mW/cm²) was irradiated onto the driedcoating membrane to perform an alignment treatment. Subsequently, inorder to increase orientation of the liquid crystal layer, the liquidcrystal layer was dried in an oven at 100° C. for about 2 minutes toprepare a liquid crystal film.

A retardance of the liquid crystal film at an incident angle of −50.00°to +50.00° was measured by using Axoscan, a device of measuring aretardance manufactured by Axomatrix. The results are illustrated inFIG. 5.

Comparative Example 1

A liquid crystal composition and liquid crystal film were prepared byusing the same method as Example 2, except that a photo-alignmentmaterial including a repeating unit represented by the followingChemical Formula C was used as a photo-alignment material.

TABLE 1 Liquid Crystal Liquid Crystal Orientation Fluidity Example 1 ◯ ◯Example 2 ◯ X Comparative X X Example 1

As described above, it can be observed as illustrated in FIGS. 2 and 3that the liquid crystal cells and liquid crystal films prepared inExamples 1 and 2 have excellent liquid crystal orientation. In addition,it can also be observed that the liquid crystal cell prepared in Example1 has liquid crystal fluidity so that the aligned state can be switchedby supply of voltage. It can be confirmed as illustrated in FIG. 5 thatthe liquid crystal film prepared in Example 2 exhibits a uniformretardance symmetrical to an incident angle of −50.00° to +50.00° andthereby is uniformly aligned in one direction. However, in the case ofComparative Example 1, it can be confirmed as illustrated in FIG. 4 thatthe liquid crystal film exhibits poor liquid crystal orientation. Inaddition, it can be confirmed as illustrated in FIGS. 6 and 7 that thereare phase-separation phenomena in the cases of Examples 1 and 2.However, it can be confirmed as illustrated in FIG. 8 that there is nophase-separation phenomenon in the case of Comparative Example 1.

The invention claimed is:
 1. A liquid crystal composition, comprising: aphoto-alignment material comprising a halogen element, that comprises aunit represented by Chemical Formula 1; and a liquid crystal compound:

wherein n represents a number of 50 to 5,000 in the above ChemicalFormula 1 and R₁ and R₂ each independently represents hydrogen, halogen,an alkyl group, or a moiety represented by the following ChemicalFormula 2, wherein at least one of the R₁ and R₂ represents a moietyrepresented by the following Chemical Formula 2,

wherein R₃ represents an alkylene group or an alkylidene group in theabove Chemical Formula 2 and R₄ to R₈ each independently representshydrogen, halogen, an alkyl group, an alkoxy group, or an allyloxygroup; and at least one of the unit represented by the above ChemicalFormula 1 and the moiety represented by the above Chemical Formula 2includes a halogen element as a substituent.
 2. The liquid crystalcomposition of claim 1, wherein the liquid crystal compound is comprisedin an amounts of 30 parts by weight to 300 parts by weight, relative to100 parts by weight of the photo-alignment material including thehalogen element.
 3. The liquid crystal composition of claim 1, whereinthe liquid crystal compound is a polymerized liquid crystal compound ora non-polymerized liquid crystal compound.
 4. The liquid crystalcomposition of claim 1, further comprising a solvent.
 5. The liquidcrystal composition of claim 4, wherein the solvent is cyclopentanone,cyclohexanone, chlorobenzene, N-methylpyrrolidone, toluene, xylene,mesitylene, cymene, dimethylsulfoxide, dimethylformamide, chloroform,gamma butyrolactone, or tetrahydrofuran.
 6. A liquid crystal film,comprising: a substrate layer; and a liquid crystal layer formed by theliquid crystal composition of claim 1 formed on the substrate layer,wherein the liquid crystal compound is present in an aligned state inthe liquid crystal layer.
 7. The liquid crystal film of claim 6, whereinthe substrate layer is a substrate layer without orientation and theliquid crystal layer is formed adjacent to the substrate layer.
 8. Theliquid crystal film of claim 6, wherein the aligned state of the liquidcrystal compound is switched by supply of a voltage.
 9. The liquidcrystal film of claim 6, wherein the liquid crystal compound ispolymerized in the aligned state to form a liquid crystal polymer. 10.The liquid crystal film of claim 6, wherein the photo-alignment materialis phase-separated from the liquid crystal compound in anorientationally ordered state in the liquid crystal layer.
 11. A methodof preparing a liquid crystal film, comprising irradiating polarizedlight onto a coating layer including the liquid crystal composition ofclaim 1 formed on a substrate layer to form a liquid crystal layer.